High performance fluids for industrial applications can include ester based fluids or non-ester based fluids or combinations of ester and non-ester based fluids.
Ester based fluids, both natural and synthetic, have long been used globally in a wide range of industrial applications as base oils that include dielectric fluids, lubricant fluids, biodiesel fluids, etc. Synthetic esters are obtained from an alcohol, having one, two, three or more hydroxyl groups, wherein the alcohol is esterified with a carboxylic acid or acid mixture. Natural esters are triglycerides of vegetable oil, algae oil or animal fats. Triglycerides are considered the esterification product of glycerol, a triol, with three molecules of fatty acids. Vegetable oils are biodegradable, nontoxic and renewably sourced, unlike conventional mineral oils. They have low volatility, high flash and fire points and good boundary lubrication properties. However, the major drawbacks of vegetable oils are their poor oxidative stability, poor hydrolytic stability and unfavorable rheological fluid properties at low temperatures which severely limit their use in industrial applications mentioned below.
Dielectric fluids are used in the electrical industry for cooling electrical equipment such as transformers, power cables, breakers and capacitors. Typically, these dielectric fluids are used in combination with solid insulation such as in liquid-filled transformers. Examples of dielectric fluids include mineral oil, high molecular weight hydrocarbons (HMWH), silicone fluid, and synthetic hydrocarbon oils (polyalpha-olefins). Such fluids must be electrically insulating, resistant to degradation, and be able to act as a heat transfer medium so that the high amount of heat generated in an electrical apparatus can be dissipated to the surrounding environment and thereby increase the life of the solid insulation.
Lubricant fluids are used as hydraulic fluids, metal working fluids, 2-cycle engine oil, process oils, chain bar oils, and greases. A lubricant fluid is typically formulated by combining a lubricant base stock, or a mixture of lubricant base stocks, with additives and other optional formulation aids. Esters of monols, diols, triols and polyols are frequently used.
Biodiesel fluids are used in primarily three markets, mass transit, marine industry and in farming. Biodiesel fluids are made from vegetable and animal oils. Biodiesel fluids offers a number of advantages over petrodiesel fuels such as enhanced biodegradation, increased flash point, reduced toxicity, lower emissions and increased lubricity. When biodiesel fluids are blended with diesel fuels, the blend has better properties. Since the biodiesel fluid has the same fatty acid profile as the parent oil or fat, its stability behavior is similar to that of its parent oil and faces similar technical issues such as its susceptibility to oxidation upon exposure to oxygen in ambient air and hydrolysis upon exposure to moisture.
As mentioned above non-ester based fluids such as mineral oil, high molecular weight hydrocarbons (HMWH), silicone fluid, and synthetic hydrocarbon oils (polyalpha-olefins) can be used as dielectric fluids. However, these fluids are not as environmentally friendly materials as ester fluids.
Additives are often added to enhance the performance of base fluids.
There is a need for an additive to improve the fluid stability of dielectric fluids, lubricant fluids and biodiesel fluids by improving the oxidative stability and hydrolytic stability of the fluids, preferably at elevated use temperatures.